"The Saudi authorities refused to give the plane carrying President Bashir permission to cross their airspace," Emad Sayed Ahmed, the presidential press secretary, told the AFP news agency on Sunday.

Ahmed said Bashir was not flying in his normal presidential aircraft but was using a plane rented from a Saudi company.

The Sudanese leader was travelling to attend Iranian President Hassan Rouhani's swearing-in before the Iranian parliament.

They said the plane didn't have permission.

Emad Sayed Ahmed, presidential spokesman

Ten leaders from around the region, including the prime minister of close Iranian ally Syria, had been due to attend Sunday's parliamentary session, Iranian reports said.

Ahmed said that when Bashir's plane entered Saudi airspace, the pilot informed authorities that it had approval "and that it was carrying President Bashir".

"But they said the plane didn't have permission," forcing it to return to Khartoum, he said.

The Hague-based International Criminal Court in 2009 and 2010 issued two warrants against Bashir for war crimes, crimes against humanity and genocide over the conflict in Sudan's Darfur region.

Khartoum's links with Iran came under scrutiny after Bashir's regime accused Israel of an October 23 strike against the Yarmouk military factory in the capital, which led to speculation that Iranian weapons were stored or manufactured there.

Israel refused all comment on Sudan's accusation about the factory blast.